We all know that childhood abuse has devastating lifelong effects, but today there's even more bad news. Not only are people who were abused as children twice as likely to suffer from depression as adults, they're also less likely to respond well to psychological and drug-based treatments for the condition.

Researchers from King's College London reviewed 26 studies that included more than 26,000 people, according toThe Guardian. Subjects were classified as probably mistreated if they'd experienced one of five situations: rejecting interaction from their mother, harsh discipline reported by a parent, unstable caregiver throughout childhood, and self-reports of harsh physical or sexual abuse. Participants who had two of these indicators were classified as definitely abused.

Those who experienced at least one of these situations in childhood were 2.27 times more likely to have recurrent depression as adults, compared to people who had no history of abuse. It's no surprise that childhood trauma can lead to lifelong mental health issues, but there was also a more troubling finding. Those who had been abused were 43% more likely to have a poor response to psychological and medicinal treatments for depression.

The researchers speculate that this could be because abuse at a young age causes biological changes. Other studies have shown that maltreated children have abnormalities int heir pre-frontal cortex that could affect things like mood regulation and attention span. Co-author Andrea Danese offered this less-than-rosy assessment:

"Even for combined treatments, patients with a history of childhood maltreatment cannot be adequately cared for ... early preventive and therapeutic interventions may be more effective."

Of course early treatment is preferable, but more often than not, a victim of childhood abuse can't even get out of the situation for years, let alone acknowledge what happened and seek help.

The study's findings are fairly bleak, but there is a small silver lining. Co-author Rudold Uher says that knowing people with a history of abuse don't respond well to traditional treatments for depression could help doctors develop new methods tailored to their "biological vulnerabilities." That may not do people much good right now, but at least there's some small comfort in knowing researchers are making an effort to better understand and treat mental illness in people who've suffered abused.